Hi Jo I am not sure whether you are still interested but as a consultant we provide a number of documents to clients with regards to proposed signal installations. One of these is the 12/5 appendix which generally specifies the signals element and the civil elements such as duct depths, chamber depths and sizes etc we specify in the 5/2 appendix. If you would like an example of this please dont hesitate to email on andy.marson@greensignals.co.uk.